Conventionally, from the view point of protecting a passenger of an automobile or the like, an air-bag device which is a passenger protective device has been widely used. An air-bag device is installed to protect a passenger from impact occurring at the time of collision of a vehicle or the like, and in the case of collision of a vehicle or the like, an air bag instantly expands and develops as a cushion to receive the body of the passenger.
A gas generator is a device incorporated into such an air-bag device, for igniting an igniter by electrification from a control unit in the case of a collision of a vehicle or the like, and combusting a gas generating agent by a flame occurring in the igniter to generate a large quantity of gas instantly, thereby expanding and developing the air bag. An air-bag device is installed, for example, in a steering wheel or an instrument panel of an automobile.
Among gas generators having a variety of structures, there is a so-called disc-type gas generator that is preferably utilized in an air-bag device of the driver's seat installed in a steering wheel or the like. A disc-type gas generator has a short cylindrical housing having closed axial end parts, and a gas discharge opening provided on the circumferential wall of the housing, and in the housing, a gas generating agent is accommodated to surround an igniter situated inside the housing, and a filter is accommodated to surround the circumference of the gas generating agent.
In this disc-type gas generator, generally, a transfer charge (enhancer agent) as a combustion promoter is disposed between the combustion chamber in which the gas generating agent is accommodated and the igniter to ensure ignition of the gas generating agent by a flame occurring in the igniter. Usually, the transfer charge is accommodated in a transfer charge chamber provided inside the cup-shaped member, and the cup-shaped member is disposed to project inside the combustion chamber so that the transfer charge chamber faces an ignition part accommodating an ignition charge of the igniter.
As the cup-shaped member, there are known a so-called enhancer holder and a so-called enhancer cup. The former is a member having high mechanical strength such as a stainless alloy and is previously provided with an opening which is closed with a sealing tape to allow breakage of the closure of the sealing tape at the time of actuation. The latter uses a member having low mechanical strength such as aluminum, to allow breakage or melting in its entire surface at the time of actuation.
Here, the cup-shaped member partitions the transfer charge chamber in which the transfer charge is accommodated and the combustion chamber in which the gas generating agent is accommodated so as to obtain intended combustion characteristics at the time of actuation of the gas generator, and need to be assembled to the housing so that at least these transfer charge and gas generating agent will not mix each other. From this point of view, conventionally, assembling of the cup-shaped member to the housing is generally conducted by swaging fixation or press-fitting fixation.
For example, in the gas generator disclosed in Japanese Patent Laying-Open No. 2010-234843 (PTD 1), a cup-shaped member is provided with a flange part, and a housing is provided with a collar part for swaging, and by swaging the collar part so that the flange part is retained by the collar part, the cup-shaped member is fixed to the housing.
For example, in the gas generator disclosed in Japanese Patent Laying-Open No. 2010-173560 (PTD 2), a projecting cylindrical part that projects toward a combustion chamber is provided at a predetermined position of a housing, and an open end of a cup-shaped member is press-fitted in the projecting cylindrical part to fix the cup-shaped member to the housing.